In Europe, skiers can usually access the slopes by train, and rail travel has plenty of advantages. As the the site, SnowCarbon.co.uk suggests about train travel: "it's better for you" and "it's better for the planet". Trains produce 90% of the carbon emissions of air travel.

Exercise bikes at the Crowne Plaza Copenhagen allow guests to generate electricity. Pedaling for 15 minutes earns exercisers a meal voucher, and creates 10-watt-hours of electricity. iPhones on the handlebars indicate the amount of power being generated.

Extreme freeskier Alison Gannett is on a mission to save our snow. Some of the glaciers she skied on a decade ago are no longer around. Gannett photographs glacier change on her ski trips, and she is a climate change solutions consultant.

Geocaching doesn't sound like it has anything to do with sustainable travel when you first hear about it. Instead, it sounds like glorified littering. Geocachers hide gizmos in urban and rural settings (read: the great outdoors).

Luckily, there are Christmas tree farms, like Yule Tree Farms and Krueger's Christmas Trees, which sustainable travel writer Jennifer Stewart mentioned earlier this month. However, Christmas tree farms ship a high percentage of their trees, and it's better to get a tree off-the-farm, if possible.